A clonal tumor cell line (PC12) has been derived from a rat pheochromocytoma. This cell line has been used as a model for neurobiologic and neuropathologic studies. The PC12 cells display differentiated properties of adrenal chromaffin cells and, in addition, acquire further neural properties to resemble sympathetic neurons after treatment with nerve growth factor (NGF). We have used immunologic techniques to identify a NGS Induced Large External (NILE) glycoprotein on the plasma membrane of PC12 cells and rat sympathetic neurons. The NILE glycoprotein is a potential surface membrane neural marker for the following reasons: It is trypsin-sensitive; surface-exposed; present only on neural tissues and NGF-inducible. The objectives of this proposal are: 1) to isolate and purify NILE glycoprotein using biochemical techniques such as affinity chromatography and SDS-polyacrylamide gel electrophoresis; 2) to prepare mono-specific antibodies to NILE glycoprotein either by immunizing a suitable recipient laboratory animal directly with NILE glycoprotein or isolate and further purify them from our heterogeneous antisera to rat sympathetic neurons using affinity chromatography; 3) to compare by morphological methods (immunoperoxidase, autoradiography) the topographic distribution of NILE glycoprotein (using monospecific anti-NILE antibodies as a probe) on the plasma membrane of perikarya and processes of PC12 cells and rat sympathetic neurons; and 4) to study the possible segregation and endocytosis of the surface NILE glycoprotein of PC12 cells and rat sympathetic neurons following exposure to anti-NILE antibodies and NGF (NGF-treated PC12 cells). This study will contribute to our understanding of the mechanism of endocytosis and turnover of a highly specific, well-characterized portion of the plasma membrane of neurons.